The purpose of this study is to determine the differential contributions made to the accurate measurement of depression by the NIMH Diagnostic Interview Schedule (DIS) and the Beck Depression Inventory (BDI). The DIS was developed under contract to the NIMH Division of Epidemiology and Biometry to be the diagnostic instrument used in a multi-million dollar collaborative epidemiologic study currently underway at four urban sites. The BDI has been selected as one of the instruments to evaluate treatment outcome in a multi-million dollar collaborative study comparing the effectiveness in the treatment of depression of cognitive/behavioral and interpersonal therapy. This study will administer these two measures concurrently to a random sample of the Greater Metropolitan St. Louis Area (N equals 300) to examine the strengths and weaknesses of each instrument and to determine the relation between them, so that results using one measure may be expressed in terms of the other. This study will also determine the psychometric properties of the BDI as a survey instrument in the unselected U.S. adult population, specifically its 2-week test-retest reliability and its validity using DSM-III diagnoses of affective disorder as the criterion. This study will also examine more intensively and over a 2-week period subjects who could be characterized as having "sub-clinical" depression, i.e. who score 10 or more on the BDI but do not qualify for a diagnosis of depression according to DSM-III. The study will prepare for the use of the BDI as a rapid, cost-effective instrument for the measurement of depression in the unselected U.S. adult population.